Background: Aging veterans are the largest growing cohort in the VHA population and pain related disorders are the most prevalent of health related conditions. Recent observational studies have raised questions about the safety and effectiveness of conventional analgesic regimens for pain treatment in older adults. In particular, these studies have raised concerns about the safety of opioids versus non-steroidal anti-inflammatory drugs (NSAIDs) of analgesics in older adults, medications commonly prescribed to veterans. Research gaps in optimal older adult pain treatment remain and more evidence-based research is needed before conclusive recommendations and guidelines can be endorsed. Objectives: The objectives of the following proposal are to expand upon the limitations of recent studies by evaluating the safety and effectiveness of 3 commonly used analgesic medications types (opioids, NSAIDs, coxibs) for patients with chronic pain. This will be done with 2 concurrent projects evaluating analgesic use in older veterans diagnosed with arthritis. The first will be a prospective cohort study, the secon will use national administrative data. Specific aims will be to determine: 1. the long-term safety of commonly used analgesic medications in older veterans diagnosed with arthritis, 2. the effectiveness of commonly used analgesic medications in older veterans diagnosed with arthritis, 3. the factors that predict positive and negative analgesic treatment outcomes for this cohort. Methods: To accomplish these objectives we will complete two projects targeting older (50+ years age) veterans with arthritis. The first study will prospectively survey older veterans with arthritis recruited from primary care clinics at four different VA centers with geographic and prescribing pattern diversity. Prospective data collection will allow us to address limitations identified with retrospective data use. These include collecting data on current pain levels, over the counter analgesic use, functional scores (including cognitive function), and health behavior factors (e.g., smoking). The second study use a national cohort of US veterans and replicate a controversial study comparing the safety of analgesics in a cohort of veterans with osteoarthritis. Using a longitudinal cohort of veterans from 2010-2014, the comparative safety of NSAIDs, selective coxibs, and opioids will be determined using both propensity score-matched cohorts and instrumental variable analyses. Veterans Health Administrative data, linked to Medicare and Medicaid claims data, will allow for a robust evaluation of patient safety outcomes.